The present invention relates to the field of brewing.
More particularly, the present invention relates to an improved liquid sampling valve used in the quantitative analysis, by gas chromatography, of alcohol and carbon dioxide in beer. Even more particularly, the present invention relates to an improved liquid sampling valve which may be used in conjunction with the method and apparatus for the quantitative analysis of carbon dioxide in beer described in the applicant's co-pending Canadian patent application No. 537,187 filed July 30, 1987 for an invention entitled GAS CHROMATOGRAPH MODIFICATION.
Currently, to test beer for alcohol (i.e. ethanol) content or any other component than CO.sub.2, it must first be de-gassed (i.e. the CO.sub.2 must be removed). This is because conventional laboratory techniques including gas chromatographic analyses are based on the exact measurement of a defined sample quantity (volume or weight); partially de-gassed or carbonated beer samples cannot be measured accurately because of the inherent instability of the sample specimen and as a consequence inaccurate analytical results are obtained. The upshot of the foregoing is it is currently impossible to determine alcohol content in beer accurately with an in-line process gas chromatographic analyzer (GCA). Hence, de-gassification of discrete samples is done prior to alcoholic content determination by a GCA.
Unfortunately, however, when beer is de-gassified prior to analysis, it is inevitable that some ethanol is lost. This further complicates the problem of alcohol determination as the discrete sample which has been de-gassed will no longer be representative of the batch from which it originated.
A further problem associated with the use of a process GCA for ethanol determination is that solids (mainly carbohydrates and proteins) from the beer tend to accumulate in the GCA, necessitating its frequent dis-assembly for cleaning.
The applicant's co-pending patent application aforesaid provides an apparatus by which the alcohol concentration and the carbon dioxide concentration in a pressurized beer sample may be gauged without de-gassing the beer. It provides an apparatus for use in the in-line chromatographic analysis of, for instance, alcohol or carbon dioxide in beer which apparatus is provided with a CIP (cleaning-in-place) for continuous operation. More particularly, that patent application relates broadly to an apparatus to measure the concentration of a constituent of a solution containing dissolved gas including: (a) conduit means connectable to a source of said solution; (b) flow control means on said conduit means, selectively to permit the flow of said solution in said conduit means; (c) pressure regulation means on said conduit means to control the pressure of said solution in said conduit means, and maintain the pressure in said conduit means at a level sufficiently high to prevent gassification of said dissolved gas in said solution, thereby to prevent foaming in said conduit means; (d) a gas chromatographic analyzer (GCA) in communication with said conduit means via a sampling valve, to permit the flow of discrete samples of said solution into said GCA for analysis, the interior of said GCA being maintained at the same pressure as in said conduit means.
The copending application also relates to a method of measuring the concentration of a constituent in a solution containing a dissolved gas, including the steps of: (a) introducing a quantity of said solution into a pressurizable conduit; (b) pressurizing said solution in said conduit, to prevent gassification of the dissolved gas in the solution; (c) providing a gas chromatographic analyzer (GCA) in communication with said conduit via a liquid sampling valve, and maintaining a pressure in said GCA equal to that in said conduit; (d) measuring the desired constituent concentration in said solution with said GCA.
Referring first to FIG. 1, which corresponds to FIG. 1 of the above referenced Canadian application, a sampling system is provided which may be used to analyze the alcohol content of beer directly from the production lines in a brewery. An analyzer 1 is connected to the production line brewery via a process beer supply line 2. The beer in the line 2 is, of course, carbonated and at sub-ambient temperatures--both of which conditions had previously to be altered before analysis, and neither of which is altered utilizing the present invention. The beer flows through an air actuated valve 3 and is drawn into the sampling area with the aid of pump 4.
The beer flows from the pump 4 to a liquid sampling valve 5, where a quantity can be diverted to a gas chromatographic analyzer 1, which is any suitable standard process GCA unit. Between the line 2 and the analyzer 1, a pressure of 80 psia is maintained in the analyzer by a pressure regulator 6 on the main sample line. Pressure is monitored with a pressure indicator 7 on this line. The pressure in the sample line is necessary to deliver a uniformly liquid sample to the analyzer. Maintenance of this pressure prevents the undesired separation of carbon dioxide from the liquid which otherwise would result in foam in the sample line. The size of the injected beer sample is predetermined and relatively small (0.5 microliter) and foam in the sample line would lead to inaccurate measurements.
The major part of the beer flowing through the sampling line will not be diverted to the analyzer, but will re returned via return line 8 and will pass through air actuated drain/process return valve 10 to process return line 9, which flows to the main production line in the brewery.
It has been found, using the system outlined above, that by maintaining back pressure in the sampling line and similar pressure in the GCA, a sample with a CO.sub.2 content can be analyzed, with no fluctuation upon vaporization in the GCA to cause unreproducable results.
To calibrate the GCA 1 calibration standard (having a known concentration of the thing to be analyzed) is taken in through line 11, past flow indicator 12 and through air actuated valves 13 and 3 to the sampling area described above, where a sample of the known standard is analyzed to calibrate the analyzer 1. Of course, a series of known standards must be analyzed before calibration of the analyzer is complete. Also, it will be noted that valve 10 will be open to drain line, rather than process return line 9 during calibration.
The system of FIG. 1 also has a clean-in-place (CIP) sub-system built into it. Lines 15 and 16 respectively feed hot water and cleaning solvent into the CIP sub-system, from whence it can be allowed to flow into the main sampling system. A pressure regulator 17 and pressure indicator 18 are provided on the hot water line, to ensure that the pressure in this line is kept at acceptable levels (as will be a matter of choice to one skilled in the brewing art and especially in plant maintenance). Also, a flow indicator is provided on the hot water line so that a suitable quantity of hot water may easily be mixed with the solvent solution in-put through line 16.
Carefully measured quantities of cleaning solution are drawn through line 16 by metering pump 20 and pass through pressure indicator 21, flow indicator 22 and valve (air actuated) 23 to mixing coil 24. At the same time as when cleaning solution is let into coil 24, air actuated valve 25 on the hot water line is opened to allow hot water into the coil 24 and after the water and solution are mixed, air actuated valve 26 is opened and valves 13 and 3 are opened to permit a flow of mixed water and cleaning solution to pass through the sampling area and clean any deposited solids therefrom.
Valve 10 should, of course, be set to drain line 14 to permit used solution to be disposed of. After the sampling system has been cleaned with cleaning solution, it is flushed with hot water by opening valve 25 to by-pass line 27 (to by-pass coils 24), closing valve 23 and opening valves 26, 13, 3 and 10 to permit hot water flow through the sampling area and out the drain.
The system of pressurized gas chromatography of the above referenced copending application may also be used in laboratory analysis of discrete samples (bottles or cans) of finished product beer, for quality control as illustrated schematically in FIG. 2.
A container 27, either a bottle or can of beer is placed in holder 28 which holds it securely while a sampling mechanism 29 is pneumatically driven into the container 27 to draw out the contents thereof. These contents flow through sampling line 30 through sampling valve 31 into the sampling loop 32 and through sampling pump 33 used to develop 80 PSI in the sampling loop 32. The loop further includes a pressure regulator 34 and pressure indicator 35, for accurate regulation and monitoring of the pressure in the loop 32.
A liquid sampling valve 36 on the loop 32 is used to divert samples to GCA 37, the column of which is kept pressurized at 80 PSI.
Completing the sampling loop is loop drain valve 38 which may be opened to drain line 39 when analysis is complete or to loop return line 40 for the actual sampling procedure. When fluid is injected into the loop from sampling mechanism 29, it fills the loop, at which time valve 38 is closed to drain line 39 and opened to loop return line 40. Simultaneously, valve 31 is closed, which completes the loop, and permits pressurization thereof. To analyze the next sample, valve 38 is opened to drain line 39 and the sample in the loop discharged; the cycle is then repeated.
The laboratory system illustrated in FIG. 2 also includes a cleaning sub-system, much modified from the fill in-line CIP system disclosed above. The cleaning sub-system of the FIG. 2 apparatus is merely a line 41 provided with a valve 42 and a flow indicator 43, into which line, and thence into the loop, may be injected cleaning solution, hot rinse water or calibration standard solution.
Since the reason for the provision of a cleaning-in-place system which washes out the entire conduit system provided in the applicant's aforesaid patent application, it is the object of the present invention to provide a modified sampling valve and a modified cleaning-in-place sub-system which overcomes the drawback identified above, and thereby decreases down-time and complexity associated with using the invention described in the applicant's aforesaid co-pending patent application.